1. Field of the Invention
The present invention relates to a washing machine, and more particularly to a washing machine having an improved structure in circulation and drain of washing water.
2. Description of the Related Art
Recently, a washing machine having a washing water circulation structure, in which washing water is pumped out of a water tub and is restored to the water tub, is being developed and manufactured to improve washing and rinsing performance of the washing machine.
Generally, the washing machine having the circulation structure includes an additional circulation pump for circulation of washing water in addition to a drain pump for drain of washing water which causes problems of complicated inner structure and increase in the manufacturing cost.
In order to improve the problems, Korean Patent Laid-open Publication No. 10-2007-059433 discloses a washing machine which performs drain and circulation operations of washing water using a single pump.
The washing machine disclosed in Korean Patent Laid-open Publication No. 10-2007-059433 includes a pump unit. The pump unit includes a pump casing having a water supply path and a plurality of drain paths, a pump which pumps washing water in the pump casing to the plurality of drain paths, and a plurality of valves installed in the pump casing to open and close the plurality of drain paths, respectively.
However, in the washing machine disclosed in Korean Patent Laid-open Publication No. 10-2007-059433, since the valves having the same number as the drain paths are necessary to open and close the plurality of drain paths, there are still problems of complicating an inner structure and increasing the manufacturing cost.
Further, in the washing machine having the above structure, the plurality of valves should be individually controlled. Thus, there are problems of complicating the control and increasing the possibility of malfunctioning valves.